docs: def _lease_valid(self, lease):
          """
          Check if the given lease exist and still has a prefix that owns it.
          If the lease exist but its prefix isn't, remove the lease from this
          store.
  
          Args:
              lease (lago.subnet_lease.Lease): Object representation of the
                  lease
  
          Returns:
              str or None: If the lease and its prefix exists, return the path
                  to the uuid of the prefix, else return None.
          """
          if not lease.exist:
              return None
  
          if lease.has_env:
              return lease.uuid_path
          else:
              self._release(lease)
              return None